Ramirez returns to the team that originally signed him as a 16-year-old from the Dominican Republic in 2000, inking a four-year deal reportedly worth $88 million.

Sandoval, less than four weeks after winning a third World Series title with the San Francisco Giants, signed for five years and a reported $95 million.

Ramirez's return to Boston is symbolic more than anything. He played just two games for the Red Sox in 2005 before they traded him to the Marlins as part of the deal that landed them pitcher Josh Beckett and third baseman Mike Lowell.

Ramirez developed into a star over 6 1/2 seasons with the Marlins. He was National League Rookie of the Year in 2006 and earned three All-Star selections before he was traded to the Dodgers in 2012.

He is a career .300 hitter while playing mostly shortstop, but has battled injuries in the past two seasons in Los Angeles. He played just 86 games in 2013 and batted .345, then hit .283 with 13 homers and 71 runs batted in over 128 games this past season.

The Red Sox said Ramirez will play left field, a new position for him.

"His willingness and openness to embracing it was really appealing to us," said Red Sox general manager Ben Cherington.

Sandoval, who spent most of his 869 games for San Francisco playing third base, was part of three World Series championships teams in the last five years, winning the series MVP award in 2012.

He is a career .294 hitter with 106 home runs, 192 doubles and 462 RBI. He batted .279 with 16 homers and 73 RBI in 157 games this past season, then set the MLB record with 26 hits in the postseason.

The two-time All-Star has been a clutch performer in postseason play with a .344 average in 39 games.

The Giants wished Sandoval luck in a statement and said he will be "greatly missed."

"I need a new challenge," Sandoval said Tuesday. "I'm happy to be here right now, I'm going to enjoy this ballpark."

Cherington said there was a lot about Sandoval that appealed to the Red Sox, who are trying to revamp an offense that tied for the second-worst batting average and slugging percentage in the American League this past season.

Boston went from a World Series title in 2013 to a last-place finish in the AL East.

"This was an opportunity to add a really great player, a great person, and a great fit for our team at a position we need," Cherington said.

The Giants had corroborated the reports of Sandoval's departure by releasing a statement on Monday that wished one of the team's most popular players well.

The Red Sox designated Ryan Lavarnway and Juan Francisco for assignment to make room on the roster for Ramirez and Sandoval.